The present invention relates generally to a fluid-handling machine, and more particularly to a radial-piston fluid-handling machine. In particular, the present invention relates to a radial-piston fluid-handling machine provided with means for preventing the separation of piston shoes from the associated pistons.
Radial-piston fluid-handling machines are already well known in the art, and require no detailed description as to their general concept and operation. Generally speaking, they have a rotor which is formed with angularly spaced radially oriented cylinder bores in each of which a piston is radially reciprocable. The outer end of the piston carries a piston shoe which is in sliding engagement with a control ring or with an inner circumferential surface of a surrounding housing, and since this surface of a control ring is eccentric with reference to the rotor, relative rotation of the rotor and the control ring will result in reciprocation of the piston. A machine of this general type is, for instance, disclosed in my own prior U.S. Pat. No. 3,223,046 to which reference may be had for further details concerning the prior art.
Generally speaking, the piston shoes via whose sliding contact with the control ring or similar instrumentality the reciprocation of the pistons is effected, are connected with the associated pistons and thus cannot become separated therefrom. The connection is usually of a type permitting a certain degree of pivoting movement of piston shoe relative to piston, which requires that the piston shoe be provided with a portion that is engaged in a seat formed in the piston. Generally, these prior-art constructions operate very well, but it has been observed that in certain circumstances--for instance if the rotor turns at high or very high speeds--the piston shoe may become detached from its seat in the piston and separate sufficiently from the latter to become wedged in the space between the rotor and the control ring or the inner control surface of the housing. When this occurs, the piston shoe is, of course, immediately broken apart into many pieces; more importantly, however, the piston shoe will within seconds so damage the rotor and the housing and/or control ring that the entire machine becomes unuseable.